It is common practice, in certain technical fields, for samples of interest to be subjected to a particular process to be supported on solid supports. For example, protein or nucleic acid samples may be supported on filters or membranes: typically such filters or membranes are made of nylon or nitrocellulose. Samples, especially biological samples (e.g. cell suspensions or tissue sections) may also be supported on slides. Typically the slides are of transparent glass.
Samples supported on slides may be processed by a number of various techniques known to those skilled in the art, which include: standard staining techniques (e.g. Gram staining of micro-organisms, haemotoxylin/eosin staining of tissue sections); immuno- and enzyme cytochemistry (e.g. peroxidase/anti-peroxidase staining); ligand binding studies; in situ hybridisation of labelled DNA or RNA probes: and in situ amplification of nucleic acids present in a sample by means of polymerase chain reaction (PCR).
Typically, such processing is at present performed manually by laboratory personnel. This renders the processing slow and subject to individual variation (from one sample to the next, and/or from one day to the next), and is tedious for the personnel concerned. Some attempts have been made to provide apparatus to facilitate the immuno-cytochemistry process. Thus, for example, Shandon Scientific Limited manufacture the "Sequenza".TM. and "Cadenza".RTM. immuno-staining apparatus. Use of the "Sequenza".TM. apparatus involves attaching a coverplate to the slide to be processed, thereby forming a narrow channel between the slide and coverplate. The coverplate comprises a funnel-like open-ended portion which, when attached to a slide, forms an open-ended chamber, into which staining reagents are manually introduced. The reagent then flows, under the influence of gravity, into the channel between the slide and the attached coverplate. When a new reagent is introduced into the well it displaces the previous reagent into a waste collection tray at the bottom of the apparatus.
The "Cadenza".RTM. apparatus utilises the same coverplate system but additionally provides programmable automated control means for applying reagents to the open-ended well of the assembled slide/coverplate.
In relation to processing of samples supported on membranes, such samples are commonly preparations of proteins (termed Western blots) or DNA (Southern blots) or RNA (Northern blots). The molecular species of interest is visualised on the supporting membrane using specific antibodies and an appropriate detection systems (in the case of Western blots) or by hybridisation with a labelled probe (in the case of Southern and Northern blots). These processing techniques currently require considerable manual processing of the membranes.
The prior art apparatus for processing samples on solid supports is therefore very simple and limited in the functions which it can perform. The present invention aims to provide apparatus capable of more general application.